Light emitting devices, such as Light Emitting Diodes (LEDs) or Laser Diodes (LDs), which use group III-V or group II-VI compound semiconductors, are capable of emitting light of various colors, such as red, green, blue, and ultraviolet light and the like, owing to developments of device materials and thin film growth technologies. Moreover, these light emitting devices are capable of emitting white light with high efficiency through use of a fluorescent substance or color combination, and have advantages of low power consumption, semi-permanent lifespan, fast response time, safety and environmental friendliness as compared to conventional light sources, such as fluorescent lamps, incandescent lamps and the like.
Accordingly, application sectors of light emitting devices are expanded up to transmitting modules of optical communication means, LED backlights to replace Cold Cathode Fluorescence Lamps (CCFLs) which serve as backlights of Liquid Crystal Display (LCD) apparatuses, white LED lighting apparatuses to replace fluorescent lamps or incandescent lamps, head lights of vehicles and traffic lights.
FIG. 1 is a view illustrating a conventional light emitting device package.
The light emitting device package 100 may include a package body 110 having a cavity, and a light emitting device 10 placed at a bottom surface of the cavity. A radiator (not shown) may be located below the package body 110.
A first lead frame 121 and a second lead frame 122 may be placed on the package body 110. The first and second lead frames 121 and 122 may extend to the bottom surface of the cavity so as to be partially placed at the bottom surface and may be electrically connected to the light emitting device 10.
The light emitting device 10 may be electrically connected to the first lead frame 121 via a conductive adhesive 130, and may be electrically connected to the second lead frame 122 via a wire 140.
The cavity is filled with a molding part 160 containing a fluorescent substance 150 to protect the light emitting device 10 and the wire 140, for example. The fluorescent substance 150 is excited by a first wavelength range of light emitted from the light emitting device 10, thereby emitting a second wavelength range of light.
However, the conventional light emitting device package has the following problems.
The light emitting device emits heat as well as the above-described first wavelength range of light, which may have a negative effect on driving of the light emitting device. In addition, light emitting devices fabricated according to the same specifications may vary slightly in terms of thermal emission. Conventionally, the light emitting device may exhibit an increase in temperature to a range of about 60˜80° C. during driving thereof, and as necessary, the temperature of the light emitting device package must be adjusted according to external environment, such as the brightness of a place where the light emitting device package is located. Accordingly, it is necessary to adjust the temperature of the light emitting device package by measuring heat at or around the light emitting device.
Further, the quantity of light emitted from the light emitting device may vary according to applied voltage, the composition of the light emitting device, or the like, and even light emitting devices fabricated according to the same specifications may vary slightly in terms of light emission. As necessary, the quantity of light of the light emitting device package must be adjusted according to external environment, such as the brightness of a place where the light emitting device package is located.
Accordingly, it is necessary to adjust the quantity of light of the light emitting device package by measuring the quantity of light at or around the light emitting device.